Pendulum Investigation

Extracts from this document...

Introduction

Physics

PENDULUM INVESTIGATION

Aim of the investigation

The aim of the pendulum investigation is to see what will happen if I change a variable whilst I swing a pendulum and see the effect which it has on the pendulums time to complete one whole swing (from where it starts, to the opposite end, and back again). This will give me an insight into what will effect the time of the swinging of the pendulum, be it weight, string length, the angle, or the swinging point.

Planning my investigation

I will set up my investigation by having a 30cm length of string. This will be cut six times as I am measuring six different lengths of string. These will include lengths of: 30, 25, 20, 15, 10 and 5 centimeters. To make my results reliable I will test them three times each, at all the lengths, and average them out, to give a more accurate measurement. I think that I can produce reliable, precise results, using this information and plan. I will have enough data to spot “misfit” results too.

Safety Issues

For safety, I will use a pair of safety goggles. This is because whilst the pendulum is swinging, it may hit me in my eyes, as the pendulum is at a similar level of height to my head.

I will also clear all the chairs, coats and bags from the vicinity as they may cause obstruction to me, other people who I work with, or people passing who may be injured.

I will take into account the string length and the weight of the pendulum. These two factors will be the basis of my prediction. This is because the longer the string, the longer the distance is to complete the full swing of the pendulum. (Illustrated in the diagrams below)

[ Picture of large string length swinging ]

[ Picture of small string length swinging ]

The weight of the pendulum will also affect the time for the pendulum to complete a full swing. This is because the less the weight, the faster something will move through the air and the heavier it is, the more resistance it creates.

Range of results

My range of results are gathered by using a string of a variable lengths from 5cm – 30cm. The test will be repeated three times to obtain a more accurate reading. I will swing the pendulum from an angle of 90º which I will measure using a protractor. This will give a constant variable of the angle which it is swung from so one time the pendulum is not swung from a higher point or lower point to the others.

In order to record these results accurately, I have recorded the amount of time it takes for ten swings, rather than one swing, as it is easier to count ten swings if each swing is only a half a second long, so I will just divide the total of ten swings by ten to give me the result of one swing. These results are recorded in the table below:

I think that my conclusion makes scientific sense, as the longer the string, the longer the pendulum takes to complete a full swing. For example, a 30cm piece of string takes 1.3 seconds on average to complete a whole swing. Another example of a smaller length string is that a 5cm piece takes on average 0.5 seconds to make a complete swing. This proves that the shorter the string, the less time it takes to complete a whole swing. These results make scientific sense.

There are ways of further investigating more factors in which I could test, such as the weight on the end of the pendulum etc. These would give me more information on how different types of factors effect the pendulum’s time to complete one full swing. It would be interesting to investigate these other factors and see if they have a similar effect. One way that would extend my current investigation on the factor of string length is by doing more tests at different lengths and at different heights. This would gain more data and I could produce a better understanding of how these new results effect the current data, either in a similar way or in a slightly different way to what I have discovered by doing this investigation.

Related GCSE Forces and Motion essays

The scatter graph between the terminal velocity and the time taken to reach it shows that the greater the time taken to reach terminal velocity, the greater the terminal velocity. This follows the law V= u+at, as the greater the product of at (acceleration and time)

* The graph line did not begin or go through the origin, as there is still molecular activity happening. Only if we look at negative temperature values will we be able to see exactly where the molecular activity stops (or begins).

There are many factors that affect the descent of an object through a liquid such as: 1) Temperature of the liquid 2) Mass* of object 3) Size/surface area of object 4 Viscosity of liquid 5) Angle of descent Temperature I would like to investigate the correlation between temperature and time of descent.

The breaking stress is the amount of stress it takes to break the material. The yield and breaking stress may differ between the three different strings. The stress at any point in a material is the applied force per unit area and is measured in Pascals (Pa).

I took a piece of string and tied a coffee mug to the end of it. I then held it out at a non-specific angle and let it swing back and forth. I watched it swing back and forth and then shortened the rope as it was swinging.

The same balls are conditioned first to 23oC and then to 45oC and dropped from a height of 100 inches onto a concrete floor (which in both cases must be at 21-25oC). At 23oC the balls must rebound at least 12 inches; at 45oC between 26 and 33 inches.

All other variables must therefore be kept constant in order to conduct a fair test and ensure results are accurate. ==> A variable such as l was not chosen as it has a more complex relationship with y and therefore if this were a variable there wouldn't be many results one could use, as y is proportional to l3.

This suggests that everything without air must have the same acceleration, which is ten m/s. This would mean that without gravity applying forces to push the helicopter downwards, it would still eventually land, because of its mass and because of this I would be made to believe that this may another reason for the acceleration of my helicopter.